Clearly, the RouteOptions attribute is used to specify options to the actual system command run by the VCS...in this case, the command it "route".
Digging through the man pages for "route" I see the following:
"In a
change or
add command where the destination and gateway are not sufficient to specify the route
(for example, , when several interfaces have the same address), the
-ifp or
-ifa modifiers may be
used to determine the interface or interface address."
So, in other words, the options for your IPMultiNICB will tie the route the e1000g0 interface (since both e1000g0 and e1000g1 are sharing the same IP address in
your situation) in order to avoid routing confusion due to interface trunking.